LED runtimes?

[Zero_Enigma]

Ok for the math heads out there perhaps you could help me out with the numbers.

I would like to know what the runtime is for the following setups :

1. 14.4v/14.8v + 3 x SSC P4 + UIB2/Nflex
2. 14.4v/14.8v + 3 x Cree Q5 + UIB2/Nflex
3. 14.4v/14.8v + 2 x SSC P4 + UIB2/Nflex
4. 14.4v/14.8v + 2 x Cree Q5 + UIB2/Nflex
5. 14.4v/14.8v + 1 x Cree Q5/SSC P4 + UIB2/Nflex

14.4v/14.8v =

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2477 4.8A

or

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3645 9A

Thanks in advance.

 

[georges80]

Ok for the math heads out there perhaps you could help me out with the numbers.

I would like to know what the runtime is for the following setups :

1. 14.4v/14.8v + 3 x SSC P4 + UIB2/Nflex
2. 14.4v/14.8v + 3 x Cree Q5 + UIB2/Nflex
3. 14.4v/14.8v + 2 x SSC P4 + UIB2/Nflex
4. 14.4v/14.8v + 2 x Cree Q5 + UIB2/Nflex
5. 14.4v/14.8v + 1 x Cree Q5/SSC P4 + UIB2/Nflex

14.4v/14.8v =

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2477 4.8A

or

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3645 9A

Thanks in advance.

Big question... WHAT CURRENT?? What Vf??

Assume bFlex/nFlex are in the 85% to 90%+ range (depending on input voltage/output voltage and output current.

Simple calculation that would give you a rough idea of power is:

Output_power = Total_vf * Current
Input_power = Output_power / efficiency (assume 85% for worst case)

Input_current = Input_power / Input_voltage

Now, if you know the amp.hour of your battery pack you'll have a good idea of runtime AT a specific current.

Given that the whole point of bFlex/nFlex is to be able to dim the light to an appropriate level, determining runtime is going to be tricky. The best you can do is determine your worst case runtime based on your highest current draw at say a nominal 14.4V (of course when the pack is fresh and closer to 16V the current draw will be less - but you're working out worst case anyway).

You could easily put the above equations into a spreadsheet (even google has a free online one) and then you can tweak things for yourself.

cheers,
george.

 

[Zero_Enigma]

vF 3.4v (350mA), 3.5v (700mA), and 3.7v (1000mA) if the x.xV is correct to the mA.

 

[georges80]

vF 3.4v (350mA), 3.5v (700mA), and 3.7v (1000mA) if the x.xV is correct to the mA.

Well, you can plug those numbers in the equations above and you'll get an idea of your runtime at specific currents.

Vf's are typically all over the place depending on bin and range - but you can still use the numbers you have to get a reasonable guesstimate.

cheers,
george.

 

[JB01245]

Here is nice program.

LED Pro
http://www.jtice.com/led_pro/led_pro.htm